Well, either CX at Narita made a mistake - which seems quite unlikley given that I was clearly booked in A class and had an AONE4 ticket - and they thought I had an F ticket, or else they have had a change of policy? Maybe somebody has made a legal challenge about involuntary downgrades, regardless of ticketing type, and they are just playing safe. Or, am I missing something here - could there be another explanation??